Possible causes of chest pain when doing push-ups include chest muscle strain, respiratory disease, myocardial ischemia, and lactic acid accumulation in chest muscles. 1. Chest muscle strain: when doing push-ups, due to the chest muscle contraction, it is easy to cause muscle strain, causing chest pain. 2. Respiratory diseases: When doing push-ups, the body develops respiratory diseases such as spontaneous pneumothorax, which in turn causes chest pain. 3. Myocardial ischemia: when doing push-ups, the body’s oxygen demand increases and blood circulation is accelerated. If myocardial function is abnormal or myocardial exertion exceeds the cardiac load, it will cause chest pain, chest tightness and other symptoms. 4. Lactic acid accumulation in the chest muscle: long time doing push-ups cause muscle exertion, muscle rapid anaerobic fermentation capacity and produce a large amount of lactic acid, lactic acid accumulation in the chest muscle, there will be chest pain and other symptoms. It is recommended that patients seek timely medical treatment to avoid delaying the condition.